Background

Liquid chromatography tandem mass spectrometry (LC-MS/MS) is used routinely in therapeutic drug monitoring, however, automating the sample pretreatment is challenging. Protein precipitation(PP) is the simplest, fastest and most widely used method for pretreatment of biological samples. Biological samples, such as serum, plasma and whole blood, are rich in soluble proteins, which must first be deproteinized before sample analysis and determination. Liquid chromatography-tandem mass spectrometry usually uses organic reagents to precipitate proteins. Conventional protein precipitation requires high-speed centrifugation, which is highly dependent on centrifugal equipment. In addition, the protein precipitation plates used in semiautomated protein pretreatment equipment require negative or positive pressure devices, which can easily clog the sieve plate without centrifugation.